ffmpeg@*: depend on fontconfig

Due to Homebrew/homebrew-core#31510, several options were removed from
the FFmpeg formula in f75cb0920. However, removing "fontconfig" while
leaving "freetype" in seems illogical since they are complementary. For
example, the "drawtext" filter depends on libfreetype, and the "font"
option for the "drawtext" filter depends on libfontconfig.

Closes #36467.

Signed-off-by: Chongyu Zhu <i@lembacon.com>

Formula/ffmpeg.rb

@@ -3,7 +3,7 @@ class Ffmpeg < Formula
   homepage "https://ffmpeg.org/"
   url "https://ffmpeg.org/releases/ffmpeg-4.1.tar.xz"
   sha256 "a38ec4d026efb58506a99ad5cd23d5a9793b4bf415f2c4c2e9c1bb444acd1994"
-  revision 2
+  revision 3
   head "https://github.com/FFmpeg/FFmpeg.git"
 
   bottle do
@@ -16,6 +16,7 @@ class Ffmpeg < Formula
   depends_on "pkg-config" => :build
   depends_on "texi2html" => :build
 
+  depends_on "fontconfig"
   depends_on "freetype"
   depends_on "frei0r"
   depends_on "lame"
@@ -57,6 +58,7 @@ class Ffmpeg < Formula
       --enable-libx265
       --enable-libxvid
       --enable-lzma
+      --enable-libfontconfig
       --enable-libfreetype
       --enable-frei0r
       --enable-libass

Formula/ffmpeg@2.8.rb

@@ -3,7 +3,7 @@ class FfmpegAT28 < Formula
   homepage "https://ffmpeg.org/"
   url "https://ffmpeg.org/releases/ffmpeg-2.8.15.tar.bz2"
   sha256 "35647f6c1f6d4a1719bc20b76bf4c26e4ccd665f46b5676c0e91c5a04622ee21"
-  revision 3
+  revision 4
 
   bottle do
     sha256 "5dc8f7042e9a58edb6a8f046f1dfa461fb1cab0f586f57128a748dd4b2428e6d" => :mojave
@@ -17,6 +17,7 @@ class FfmpegAT28 < Formula
   depends_on "texi2html" => :build
   depends_on "yasm" => :build
 
+  depends_on "fontconfig"
   depends_on "freetype"
   depends_on "frei0r"
   depends_on "lame"
@@ -64,6 +65,7 @@ class FfmpegAT28 < Formula
       --enable-libx264
       --enable-libx265
       --enable-libxvid
+      --enable-libfontconfig
       --enable-libfreetype
       --enable-frei0r
       --enable-libass